Merge pull request #36 from hmourit/master

Added random moving behavior for enemy when player is not in range.
Added enemy sprites: Newton, Mr. H, nazists and wolves. I think it's
enough for levels 2 and 3.
Made levels 2 and 3 with dumb, pacifist enemies.
Merge pull request #37 from dgalaktionov/master

Made two levels with enemies
Hot fix, nevermind the bow
Merge pull request #40 from dgalaktionov/master

Fixed #38
Refucktored it a bit, now scene is passed as a parameter for every
entity update.
Merge pull request #41 from dgalaktionov/master

Now scene is passed as an update parameter for every Entity
Added a nice bow
Added a rifle. No bayonet yet, and maybe never.
Added laser weapons, and also a nice bang flare for lasers and rifles
Added Apple grenades. Steve Jobs would be proud.
Got the enemies armed!
Merge pull request #43 from dgalaktionov/master

Made all the weapons
Now enemies don't overlap (at least not much). Little refactor of sprite position assignment.